Muscle Function Lab

Contracting Muscle




Rubber Ball




Submerging my Hand in Icewater

Muscle Contraction Cycle http://people.emich.edu/pbogle/PHED_200/outlines/chapter_08/outline.htm

Mechanism of Muscle Contraction

http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-1.htm)

Muscle Function Lab

Introduction: This lab is designed to show a person how his / her muscles react to environmental changes, such as temperature, and fatigue. It is important to understand the basic function of our muscles for many reasons, including understanding how to exercise effectively, and how our bodies and muscles react to environmental changes. Here, we will test how our muscles contract normally, and how these contractions change when introduced to other circumstances, such as fatigue from overuse and drastic temperature changes.

1. Muscle Action: Place your fingers along the angle of your jaw just in front of your ear. Grit your teeth and observe what happens to the hardness of the
muscles in your cheek.
They become hard.

2. With the thumb and little finger of one hand, span the opposite arm's
biceps (front muscle of the upper arm) from the elbow to as close to the
shoulder as possible. Bend the arm and observe the change in the length of
the muscle. It shortens / contracts.

3. Wrap a strip of paper around your upper arm and mark the circumference
of your arm on the paper. Clench your fist tightly and mark the new
circumference on the paper. Observe what happens to the circumference of
the muscle. Increases.

Effect of Temperature on Muscle Action

1. Count the number of times you can make a fist in 20 seconds. Start with
your hand completely outstretched and make a tight fist each time. Do it
as rapidly as you can. Record the count: 24.

2. Now submerge your hand in a dishpan of water to which has been added
snow or ice so that the temperature is near the freezing point. Leave your
hand in the water for one full minute.

3. Remove your hand and immediately count how many forceful fists you can
make in 20 seconds. Record in Figure 1.
Number of Fists “Normal”: 24
Number of Fists “Ice Water”: 20

4. Effect of Fatigue on Muscle Action

1. Count how many times you can tightly squeeze a rubber ball in your hand
in 20 seconds. Record figure: 45

2. Repeat the squeezing nine more times and record results. Do not rest
between trials.

Number of rubber ball squeezes in 20 seconds / 10 Repetitions

1st: 45
2nd: 45
3rd: 44
4th: 43
5th: 44
6th: 44
7th: 41
8th: 41
9th: 40
10th: 39

ANALYSIS OF DATA:

1. What are the three changes you observed in a muscle while it is working (contracted)?
A. When you flex a muscle, it becomes larger and / or harder.
B. Your body temperature directly affects the ability of the muscle to perform: when the muscle is submerged in ice water, (and you get over the physical pain), :) the muscle is unable to perform as efficiently and as much as it could at normal temperature.
C. When you use a muscle repeatedly in a period of time, it becomes fatigued, and is unable to perform as efficiently and as much as it could at rest.
2. What effect did the cold temperature have on the action of your hand muscles? Explain.
- First, I was very surprised at the amount of pain that was involved in holding my hand in ice water for a full minute. I kept wanting to take it out of the water! But I held it in, and I felt the “pins and needles” pain go up my arm! (Sensory neurons!) :) After I took it out and repeated the exercise of fist clenching, I found that it was much more difficult to make the fist than it was before, and it occurred at a much slower rate. (I was only able to make 20 fists as opposed to 24) 3. (Graph)
4. What effect did fatigue have on the action of your hand muscles? Explain. Fatigue makes your muscles tired. A tired muscle cannot perform as well or do as many repetitions as it can when it is rested. The first time I squeezed the ball in 20 seconds, when my muscle was rested, I squeezed it 45 times. That number gradually dropped as I continued the repetitions. By the tenth repetition, I could only squeeze it 39 times.

* Conclusion:
Muscles contract and break down ATP for the energy they need. When this happens, heat is released throughout the body. When you submerge your hand in ice water, it becomes harder to contract your muscles. This must mean that ATP does not break down well in a cold environment, so it is harder to contract your muscles, and therefore harder to spread heat throughout your body. Muscle contractions keep blood moving, so when you contract them less, there is less blood flow, also making it harder to contract the muscle.

When the nervous system stimulates a muscle, sarcolemma (the cell's plasma membrane) forms T tubules that penetrate, or dip down into, the cell so that they come into contact but do not fuse with expanded portions of the sarcoplasmic reticulum. These expanded portions of the sarcoplasmic reticulum are calcium storage sites, and calcium is essential for muscle contraction, so it is released from the sarcoplasmic reticulum. Myofibrils, found in the sarcoplasmic reticulum are the contractile portions of the muscle fibers. Motor neurons stimulate the muscle fibers to contract, as the sarcomeres in the myofibrils shorten. Muscle relaxes when Ca2+ returns to sarcoplasmic reticulum. During the 10 repetitions of squeezing the ball, we were specifically told not to rest between the repetitions, so calcium did not have a chance to return to the sarcoplasmic reticulum. Therefore, the amount of calcium that is released becomes less because you are using it faster than it is being replenished. It seems that when you repeat this process several times, the muscle slows down. Perhaps the motor nuerons cannot act as quickly so the impulse travels more slowly. When submerged in ice water, perhaps the actin-myosin units (sarcomeres) take longer to shorten, and therefore longer to contract.

Compendium Review Chapter 12 Pictures

Bone Marrow

Muscular Dystrophy in Human

Muscular Dystrophy Stem Cells in Mice

Tendinitis

Fast- Twitch Muscle Fibers

Muscle Contraction Requires Energy: 3 Ways

Compendium Review Chapter 12 (Cont'd)

IV. Whole Muscle Contraction, Cont'd.
V. Muscular Disorders
VI. Homeostasis

IV. Whole Muscle Contraction, Cont'd.
2. Fermentation: Produces 2 ATP from the breakdown of glucose to lactate anaerobically.
- Most likely to begin with glycogen.
- Hormones signal muscle cells to break down glycogen, making glucose available.
- Fast-acting, but results in buildup of lactate, which produces short-term muscle aches and fatigue upon exercising.
- Oxygen-debt: Continuous intake of oxygen. Required to complete the metabolism of lactate and bring cells back to their original energy state.
- Lactate is brought to liver, and 20% is broken down into carbon dioxide and water.
- ATP is gained, and then it reconverts 80% of lactate to glucose and glycogen.
3. Cellular Respiration:
- Myoglobin: molecule that combines with ans stores oxygen.
- Makes use of glucose from the breakdown of glycogen stored in muscle, blood, and fatty acids. (Mader 237)
(Insert Muscle Contraction Requires Energy picture / Frolich PowerPoint Slide 11)
D. Fast-Twitch and Slow-Twitch Muscle Fibers
1d. All muscle fibers metabolize both aerobically and anaerobically.
2d. Fast-Twitch fibers: Usually rely on creatine phophate pathway and fermentation, which are anaerobic (no oxygen required).
- Designed for strength because their motor units have many fibers.
- Provide explosions of energy.
- Light in color / fewer mitochondria, little or not myoglobin, and fewer blood vessels than Slow-Twitch fibers.
- Maximum tension is greater.
- Vulnerable to accumulation of lactate.
(Insert Fast-Twitch Muscle Fibers picture / www.muscleandstrength.com / http://www.muscleandstrength.com/articles/muscle-and-muscle-fibers.html)
3d. Slow-Twitch Muscle Fibers: Prefer Cellular Respiration (aerobic).
- Steadier tug, more endurance.
- Tire only when fuel supply is gone.
- Many mitochondria, dark in color, because of myoglobin (Respiratory pigment found in muscles.)
- Surrounded by thick capillary beds, draw more blood and oxygen.
- Low maximum tension.
- Highly resistant to fatigue.
- A high reserve of glycogen and fat, so mitochondria can keep a steady prolonged production of ATP as long as oxygen is available.
E. Delayed Onset Muscle Soreness:
- Due to tissue injury.
- Happens when muscles contract while lengthening. (Mader 239)
V. Muscular Disorders: Common VS Serious.
A. Common:
1a. Spasms: Sudden, involuntary muscular contractions usually accompanied by pain. (Smooth and Skeletal.)
2a. Convulsion: Multiple spasms.
3a. Cramps: Strong, painful spasms, usually due to strenuous activities.
4a. Facial Tics: Spasms controlled voluntarily, but with great effort. (ie, periodic eye blinking.)
5a. Tendinitis: Normal, smooth gliding motion of tendon is impaired, tendon is inflamed, and movement of joint becomes painful.
- Mostly caused by overuse.
(Insert Tendinitis picture / www.ktvu.com / http://www.ktvu.com/encyclopedia/6867816/detail.html)
6a. Bursitis: An inflammation of the bursa, which provides a smooth, slippery surface where muscles and tendons glide over bones.
- Results from repetitive movement or from prolonged and excessive pressure.
B. Muscular Diseases: More serious, requiring medical care.
1b. Myalgia: Achy muscles.
- Most common cause is either overuse or overstretching.
2b. Fibromyalgia: Chronic condition.
- Symptoms: achy pain, tenderness, and stiffness of muscles.
3b. Muscular Dystrophy: A group of disorders characterized by a progressive degeneration and weakening of muscles.
- As muscle fibers die, fat and connective tissue take their place.
- Duchenne Muscular Dystrophy: Most common.
- Inherited through flawed gene carried by mother.
- Caused by protein dystrophin.
(Insert Muscular Dystrophy Stem Cells in Mice picture / www.dogflu.ca / http://www.dogflu.ca/health/news?from=630)
(Insert Muscular Dystrophy in Human picture / www.dinf.ne.jp / http://www.dinf.ne.jp/doc/english/global/david/dwe002/dwe00212.htm)
4b. Myasthenia Gravis: Autoimmune disease characterized by weakness in muscles of eyelids, face, neck and extremities.
5b. Amyotrophic Lateral Sclerosis: (Lou Gehrig's disease).
- Gradual loss of ability to walk, talk, chew, and swallow.
- Mental abilities and sensations are not affected. (Mader 240)
VI. Homeostasis
A. Both the muscular and skeletal systems contribute to homeostasis.
B. Both Systems Produce Movement.
- Body movements allow us to respond to certain types of changes in environment: (ie moving into shade when you are hot.)
- Other movements, like the skeletal muscles allowing the jaw and tongue to move, are necessary for supplying body's cells with nutrients.
C. Both Systems Protect Body Parts.
- Skeletal protects soft internal organs.
- Muscular pads bones, offering protection for abdominal organs.
D. Both Store and Release Calcium:
- Calcium is essential for muscle contraction and nerve conduction.
- Necessary for regulation of cellular metabolism.
- Skeleton is a reservoir for storing calcium.
E. Blood Cells are Produced in Bones:
- Red bone marrow is the site of blood cell production. They also carry oxygen in blood.
- White blood cells originate in red bone marrow, and are necessary to defend your body.
- Bones contain yellow and red bone marrow. Fat is stored in yellow.
(Insert Bone Marrow picture / www.drstandley.com / http://www.drstandley.com/bodysystems_skeletal.shtml)
F. Muscles Help Maintain Body Temperature:
1f. When you are cold, smooth muscles in blood vessels that supply your skin constrict, reducing amount of blood that is close to surface of body. Conserves heat.
2f. Skeletal muscle contraction requires ATP, and using ATP generates heat.

Compendium Review Chapter 12

(Smooth Muscle) Should be at bottom.

Skeletal Muscle Fiber Structure and Functions
(Should be placed two pics down... oops!)

Neuromuscular Junction

Mechanism of Muscle Control

Parts of Muscle Cell

Anatomy of Skeletal Muscles

Skeletal Muscles Work in Pairs

Skeletal Muscle

Cardiac Muscle

I. Overview of the Muscular System
II. Skeletal Muscle Fiber Contraction
III. Whole Muscle Contraction

I. Overview of the Muscular System
A. All muscles contract, and when they do, some part of the body moves.
B. Types of Muscles: Three types. Cells of these tissues are called muscle fibers.
1b. Smooth Muscle: These fibers are spindle-shaped cells, each with a single nucleus.
- Usually arranged in parallel lines, forming sheets.
- No striations.
- Found in walls of hollow internal organs, and it makes these walls contract.
- Contraction is involuntary.
- Slower to contract than skeletal muscle, but can sustain prolonged contractions and does not tire easily.
(Insert Smooth Muscle picture / http://www.east-haven.k12.ct.us/ / http://www.east-haven.k12.ct.us/eha/grade6/system6/smoothcardiacmusclekc/indexkc.htm)
2b. Cardiac Muscle: Forms heart walls.
- Fibers are generically without nuclues, striated, tubular, and branched.
- Branching allows fibers to interlock at intercalated disks.
- Plasma membranes at intercalated disks have gap junctions allowing contractions to spread quickly throughout wall of heart.
- Fibers relax completely between contractions.
- Involuntary contractions.
(Insert Cardiac Muscle picture / http://www.east-haven.k12.ct.us/ / http://www.east-haven.k12.ct.us/eha/grade6/system6/smoothcardiacmusclekc/indexkc.htm)
3b. Skeletal Muscle: Skeletal muscles that attach to the skeleton.
- Fibers are tubular, multinucleated, and striated.
- Run the length of the muscle and can be very long.
- Voluntary: we decide when to move a particular body part, like arms and legs.
- Contraction causes movement of bones at joint.
(Insert Skeletal Muscle picture / oregonstate.edu / http://rds.yahoo.com/_ylt=A0S020qgTXBIJTIB1K6jzbkF/SIG=1367v0nr2/EXP=1215405856/**http%3A//oregonstate.edu/~peila/Pharmstuff/Projector%2520Slides/Projector%2520Slides"
C. Functions of Skeletal Muscles
1c. Support the body. Allows us to remain upright.
2c. Make bones move: Contractions move arms, legs, eyes, facial expressions, and breathing.
- Rigor Mortis: Muscle contractions at death.
3c. Help maintain a constant body temp.
- Muscle contractions causes ATP to break down, releasing heat to spread throughout the body.
3c. Assists movement in cardiovascular and lymphatic vessels.
- Pressure of contraction keeps blood moving in cardiovascular veins and lymph moving in lymphatic vessles.
4c. Help protect internal organs and stabilize joints- Muscles pad bones.
- Muscular wall in abdominal region protects internal organs.
- Muscle tendons help hold bones and joints together.
D. Skeletal Muscles of Body:
- Humans are vertebrates: skeletal muscles lie outside an internal skeleton that has jointed appendages.
1d. Basic Structure of Skeletal Muscles:
- Well-orgnized.
- Contains fascicles: Bundles of skeletal muscle fibers in whole muscle.
- Each fascicle is surrounded by connective tissue, and so are the fibers within the fascicles.
- Fascia: Covers muscles. Type of connective tissue that extends beyond the muscle and becomes a tendon.
2d. Work in pairs:
- Origin of a muscle is on a stationary bone, and the insertion of a muscle is on a bone that moves.
- Muscle contracts, it pulls on tendons at its insertion, and bone moves.
- Function in groups. So, nervous system stimulates a group of muscles, not a single.
- However, one muscle does most of work and is called a prime mover.
- Synergists: Muscles that assist the prime mover.
- Muscles shorten when they contract. They can only pull, not push.
- So, they work in opposite pairs. Antagonist: the muscle that acts opposite to a prime mover.
- Smooth muscle movements depend on an antagonist relaxing when a prime mover contracts. (Mader 228-229)
(Insert Skeletal Muscle Work in Pairs picture / Frolich PowerPoint Slide 11)
E. Names and Actions of Skeletal Muscles:
1e. Names of Skeletal Muscles are often cominations of the following terms:
- Size: Minimus, Maximus, Vastus (huge), Longus, and Brevis (short).
- Shape: Deltoid, Trapezius, Latissimus (wide), and Terres (round).
- Location: External, Internal, Frontalis, Pectoralis (chest), Gluteus (buttock), Brachii (arm), and Sub (beneath).
- Direction of Muscle Fibers: Rectus (straight), Orbicularis (circular), Transverse ( across), and Oblique (diagonal).
- Attachment: Where and / or to what the muscle attaches. Ex. Brachioradialis: Attached to the brachium (arm) and the radius.
- Number of Attachments: Ex. Biceps (two attachments), or origi- Action: Ex. Extensor digitorum extends the fingers. Adduction- movement of a body part toward the midline. Other terms: Flexor, Masseter (chew), and levator (lift). (Mader 230-231)
(Insert Anatomy of Skeletal Muscles picture / http://www.doereport.com/ / http://rds.yahoo.com/_ylt=A0S0207GV3BIQBQACPGjzbkF/SIG=12aro790h/EXP=1215408454/**http%3A//www.doereport.com/generateexhibit.php%3FID=8106 )
II. Skeletal Muscle Fiber Contraction
A. Muscle Fibers and How They Slide
- "Muscle cells are large—visible with naked eye as “fibers of meat/chicken/fish". (Frolich PowerPoint Slide 5)
1a. Muscle Fiber: Cell containing the usual cellular components, with different names given to some of the combonents.
- Sarcolemma: Plasma Membrane.
- Sarcoplasm: Cytoplasm.
- Sarcoplasmic Reticulum: Endoplasmic reticulum.
(Insert Parts of Muscle Cell picture / Frolich PowerPoint Slide 6)
2a. Unique Anatomical Characteristics:
- T (for transverse) System: Sarcolemma forms T tubules that penetrate, or dip down into, the cell so that they come into contact but do not fuse with expanded portions of the sarcoplasmic reticulum.
- These expanded portions of the sarcoplasmic reticulum are calcium storage sites, and calcium is essentail for muscle contraction.
3a. Myofibrils: Hundreds and sometimes thousands of these, found in the sarcoplasmic reticulum, are the contractile portions of the muscle fibers.
- All other organelles are found in the sarcoplasm between the myofibrils.
- Sarcoplasm also contains glycogen, which provides stored energy for muscle contraction.
- Also contains red pigment myoglobin, which binds oxygen until it is needed for muscle contraction.
B. Myofibrils and Sarcomeres:
1b. Myofibrils: Cylindrical. Along the length of muscle fiber.
- Striations: light and dark bands, formed by placement of myofilaments within myofibrils called sarcomeres.
2b. Sarcomeres: Extends between two dark lines called Z lines.
- Contains two types of protein myofilaments.
- Thick filaments: Composed of a protein called Myosin.
- Thin filaments: Composed of a protein called Actin.
C. Myofilaments: The thick and thin filaments differ in the following ways:
1c. Thick Filaments: Composed of several hundred molecules of protein myosin.
- Myosin molecules are shaped like golf clubs. "Head" is called "Crossbridge", which occurs on each side of a sarcomere but not the middle.
2c. Thin Filaments: Made up of two intertwining strands of the protein actin.
- Tropomyosin and Troponin are two other proteins involved.
3c. Sliding Filaments:
- Muscles are stimulated, impulses travel down a T tubule, and calcium is realeased from sarcoplasmic reticulum.
- Muscle fiber contracts as the sarcomeres in the myofibrils shorten.
- When a sarcomere shortens, the actin (thin filaments) slide past the myosin (thick filaments) and approach one another.
- This makes the I band shorten, the Z line move inward, and the H zone disappear.
- Sliding Filament Model: This movement of actin filaments in relation to myosin filaments during muscle contraction.
(Insert Skeletal Muscle Fiber Structure and Functions picture / Frolich Powerpoint Slide 5)
- During the sliding process, the sarcomere shortens, though the filaments themselves remain the same length. ATP supplies energy, and the myosin filaments break down ATP, and their cross-bridges pull the actin filaments toward the center of the sarcomere. (Mader 232)
(Insert Mechanism of Muscle Contraction picture / courses.cm.utexas.edu / http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-1.htm)
D. Control of Muscle Fiber Contraction:
1d. "Neuron brings impulse to synapse with muscle." (Frolich PowerPoint Slide 4).
- Motor Neurons stimulate muscle fibers to contract. Their axons are in nerves.
- This axon can stimulate a few to several muscle fibers because each axon has several branches.
- Each branch ends in an axon terminal that is close to the sarcolemma of a muscle fiber.
- Synaptic cleft: small gap separating the axon terminal from the sarcolemma.
- Neuromuscular Junction: Name for this entire region.
(Insert Neuromuscular Junction picture / Frolich PowerPoint Slide 4)
2d. Axon terminals have synaptic vesicles filled with neurotransmitter acetylcholine (ACh).
- When a nerve impulses, (traveling down a motor neuron), it arrives at an axon terminal, where the synaptic vesicles release ACh into the synaptic cleft.
- When ACh is released, it diffuses across the cleft and binds to receptors in the sarcolemma.
- Sarcolemma gives impulses that spread over the sarcolemma and down T tubules to the sarcoplasmic reticulum. (Mader 234)
- Ca2+ is released from the sarcoplasmic reticulum and leads to sarcomere contraction.
- Muscle relaxes when Ca2+ returns to sarcoplasmic reticulum. (Mader 232)
- Sooo, in a nutshell: Calcium release occurs in the following manner:
- Motor neuron impulse arrives to axonal terminus.
- Neuro-muscular junction synapse passes message on to muscle cell.
- Sarcolemma (muscle cell membrane) undergoes action potential all along length of cell membrane and into T-tubule system.
- Voltage change causes release of Ca+2 ions into muscle cell.
- Calcium causes actin-myosin units (sarcomeres) to shorten. (Frolich PowerPoint Slide 7)
- " Muscle cells shorten by sliding protein filaments (actin-myosin units)" (Frolich PowerPoint Slide 4)
- "Movements at protein level cause whole muscle to rapidly shorten or contract." (Frolich PowerPoint Slide 4)
- The protein Tropomysin wraps around an actin filament, and troponin occurs at intervals along the threads.
- Myosin can then bind with actin.
III. Whole Muscle Contraction
A. Dependent on muscle fiber contraction.
1a. Muscles Have Motor Units:
- Motor Unit: A nerve fiber and all of the muscle fibers it innervates.
- All-or-None Law: All muscle fibers in a motor unit are stimulated at once, and they either ALL contract, or none contract.
- Variable of Interest: Number of muscle fibers within a motor unit.
2a. Muscle Twitch: Occurs when a motor unit is stimulated by infrequent electrical imulses, and a single contraction occurs that lasts a fraction of a second. Divided into three periods:
- Latent period: Time between stimulation and initiation of a contraction.
- Contraction period: Muscle shortens.
- Relaxation period: Muscle returns to former length.
3a. Summation: Increased muscle contraction until maximal sustained contraction (tetanus) is achieved.
- Muscles fatigue due to use of energy reserves.
- Recruitment: When the intensity of nervous stimulation increases, more and more motor units in a muscle are activated.
- Maximum contraction of a muscle occurs when all motor units undergo tetanic contraction. (Rare, to avoid all of the fatiguing at the same time.)
- Muscle Tone: Firm and solid muscle.
B. Energy for Muscle Contraction: Various fuel sources for energy, various ways of producing ATP. 4 possible energy sources:
1b. Fuel Sources for Exercise:
- Glycogen and fat (triglycerides), stored in muscles.
- Blood glucose and plasma fatty acids in blood.
* Adipose Tissue: Source of plasma fatty acids that muscle burns as energy source.
* Both delivered to muscles through circulating blood.
C. Sources of ATP for Muscle Contraction:
1c. Muscle cells can acquire more ATP needed for contraction once stored ATP has been used up in three ways:
1. Formation of ATP by the creatine phosphate pathway.
- Simplest and fastest, only one reaction.
- Occurs in the midst of sliding filaments.
- Creatine phosphate is formed when a muscle cell is resting.
(Mader 236-237)

Compendium Review Chapter 11

Full Skeleton: Note Appendicular Skeleton

Interesting pic of rib cage! :)

Vertebral Column



Bones of Skull


Axial Skeleton

Spiral Fracture


Bone Remodeling


Epiphyseal Plate 2


Epiphyseal Plate

Long Bone


Skeletal System

I. Overview of Skeletal System
II. Bone Growth, Remodeling and Repair
III. Bones of the Axial Skeleton

IV. Bones of the Appendicular Skeleton
V. Articulations

I. Overview of Skeletal System
A. Consists of the bones, cartilage, and fibrous connective tissue, found in ligaments at the joints.
(Insert Skeletal System picture / hsc.csu.edu.au / http://rds.yahoo.com/_ylt=A0S020uaM21In60AXlSjzbkF/SIG=12ni7sovr/EXP=1215202586/**http%3A//hsc.csu.edu.au/senior_science/core/bionics/9_3_3/933net.html)
B. Functions of the Skeleton
- Supports the body.
- Protects soft parts of body.
- Produces blood cells.
- Stores minerals and fats.
-Permits flexible body movement (w/ muscles.)
C. Anatomy of Long Bone
A. Main portion (shaft) is the diaphysis.
- Diaphysis has a large medullary cavity, (a hollow tube- Frolich PowerPoint Slide 19) whose walls are made of compact bone.
- Lined with thin, vascular membrane (endosteum).
- Filled with yellow bone marrow that stores fat.
B. Epiphyses: Expanded region at end of long bone.
- Composed mostly of spongy bone that contains red bone marrow, where blood cells are made.
- Coated with thin layer of hyaline cartilage, called articular cartilage, because it occurs at joint.
- Periosteum: A layer of fibrous connective tissue that covers all of a long bone except the articular cartilage on end of bone. Covering contains blood vessels, lymphatic vessels, and nerves.
C. Bone:
1c. Compact Bone: Highly organized and made of tubular units called osteons.
- Osteocytes: Bone cells that lie in the lacunae within the osteon.
2c. Spongy Bone: Unorganized appearance. Contains numerous thin plates (trabeculae)separated by unequal spaces.
- Lighter than compact bone, but still designed for strength.
- Trabeculae follow lines of stress, as supporters.
- Spaces are often filled with red bone marrow, a tissue that makes all types of blood cells.
D. Cartilage:
1d. Not as strong as bone.
- More flexible because the matrix is gel-like and contains collagen and elastic fibers.
- Chondrocytes: Cells of cartilage that like within lacunae that are irregularly grouped.
- No nerves.
- Suited for padding joints.
- No blood vessels, so it is slow to heal.
2d. Three types:
- Hyaline Cartilage: Firm and somewhat flexible. Matrix is uniform and glassy, but has a good supply of collagen fibers. Found at end of long bones, in nose, ends of ribs, and in larynx and trachea.
- Fibrocartilage: Stronger than hyaline, because matrix has rows of thick collagen fibers. Can withstand pressure and tension. Found in disks located between vertebrae and in cartilage of the knees.
- Elastic Cartilage: More flexible than hyaline, because matrix has mostly elastin fibers. Found in ear flaps and epiglottis.
E. Fibrous Connective Tissue: Contains rows of cells called fibroblasts separated by bundles of collagenous fibers. (Mader 208)

- Organized in layers around blood vessels. (Frolich PowerPoint Slide 16)
1e. Ligaments: Made of fibrous connective tissue. Connects bone to bone.
2e. Tendons: Made up of fibrous connective tissue. Connect muscles to a bone at joints (articulations.) (Mader 208)
(Insert Anatomy of Long Bone picture / pathologyoutlines.com / http://rds.yahoo.com/_ylt=A0S0200ORG1Iw3gB8qyjzbkF/SIG=11q06s9k7/EXP=1215206798/**http%3A//pathologyoutlines.com/bone.html )
II. Bone Growth, Remodeling and Repair

A. Bones are made up of living tissues, and they can grow, remodel, and repair. (Mader 208)

- Has nerves, blood supply, cells. (Frolich PowerPoint Slide 16)
1a. Types of cells involved in growth, remodeling and repair:
- Osteoblasts: Bone-forming cells. Secrete organic matrix of bone and promote the deposition of calcium salts into the matrix.
- Osteocytes: Mature bone cells derived from osteoblasts. Maintain structure of bone.
- Osteoclasts: Bone-absorbing cells. Break down bone and assist in depositing calcium and phosphate in blood.
B. Remodeling: Bones can grow throughout an entire lifetime by changing size, shape, and strength in response to stress.
C. Bone Repair: If a bone fractures, it can heal.
D. Bone Development and Growth:
1d. Ossification: Formation of bone.
2d. Skeleton begins forming at 6 weeks gestation, through intramembranous ossification and endochondal ossification.
* Intramembranous Ossification: Ex. Flat bones, like those of the skull.
- Bones develop between sheets of fibrous connective tissue.
- Cells that are made from connective tissue cells become osteoblasts, and they are housed in ossification centers.
- Osteoblasts secrete the organic matrix of bone. They also promote calcification.
- Periosteum forms outside the spongy bone and osteoblasts, and they carry out further ossification.
- Trabeculae form and fuse to become compact bone.
* Endochrondral Ossification: Most bones of human skeleton are formed by this method.
- Bone replaces cartilaginous models of bones.
- Cartilage is gradually replaced by calcified bone matrix.
- Bone formation spreads from center to ends.
3d. The Cartilage Model:
- Chondrocytes lay down hyaline cartilage, in the shape of future bones.
- As the models calcify, chondrocytes die.
4d. The Bone Collar:
- Osteoblasts (from periosteum) secrete the organic bone matrix, which undergoes calcification, resulting in bone collar.
- Bone collar (made of compact bone) covers the diaphysis.
5d. The Primary Ossification Center:
- Blood vessels bring osteoblasts to the interior, and they lay down spongy bone. Called the primary ossification center.
6d. The Medullary Cavity and Secondary Ossification Sites:
- Spongy bone of diaphysis is absorbed by osteoclasts, and the cavity created becomes the medullary cavity.
- Shortly after birth, secondary ossification centers form in the epiphyses.
- Red bone marrow is present in spongy bone in epiphyses.
- Cartilage is present in the epiphyseal (growth) plate and articular cartilage.
7d. The Epiphyseal (Growth) Plate:
- Band of cartilage remains between primary ossification center and each secondary center. (Mader 211)

- "Bone growth occurs at cartilaginous growth plate between diaphysis and epiphysis at either end of bone." (Frolich PowerPoint Slide 18)
(Insert Epiphyesal Plate pictures 1 & 2 / oregonstate.edu / http://rds.yahoo.com/_ylt=A0S0207MT21I9HMBZfyjzbkF/SIG=136pqoher/EXP=1215209804/**http%3A//oregonstate.edu/~peila/Pharmstuff/Projector%2520Slides/Projector%2520Slides & http://www.kort.com/ / http://rds.yahoo.com/_ylt=A0S020r2UG1IPxwBI8ajzbkF/SIG=13m4s38mn/EXP=1215210102/**http%3A//www.kort.com/cond_injuries_topic.aspx%3FtID=192c44869f07e0f9a0099b5f676b60d4%26amp;catID=46)
- When the epiphyseal plates close, growth in bone length stops. For women, this happens around age 18, age 20 for men.
E. Hormones Affect Bone Growth:
1e. Growth Hormone: A chemical messenger that affects bone growth.
- Directly stimulates growth of the epiphyseal plate, and bone growth in general.
- Works in conjunction with the metabolic activity of cells.
- Thyroid hormone promotes the metabolic activity of cells.
F. Bone Remodeling and Its Role in Homeostasis
1f. Bone is constantly broken down by osteoclasts and rebuilt by osteoblasts in an adult.
- Approx. 18% of bone is recycled per year. = Bone remodeling.
- Keeps bones strong.
- Allows body to regulate amount of calcium in blood, which is required for blood clotting.
- Bones are storage sites for calcium. (Mader 210-212)

- Calcium is needed for many aspects of cell metabolism, but is especially crucial to muscle cells. (Frolich PowerPoint Slide 20)
- Hormones involved in regulating blood calcium level: Parathyroid hormone, which accelerates bone recycling and increases blood calcium level, and Calcitonin that acts opposite to PTH. (Mader 210-212)

- Osteoporosis: Result of calcium need outweighing bone support role. Most common in women, and the elderly. Bone is broken down by osteoclasts faster than it is formed by osteoblasts. (Frolich PowerPoint Slide 21)
- Exercise keeps bones strong because they stimulate the work of osteoblasts instead of osteoclasts. (Mader 210-212)
(Insert Bone Remodeling picture / http://www.octusa.com/ / http://rds.yahoo.com/_ylt=A0S020umVG1IZ9UAqqejzbkF/SIG=123mm20gh/EXP=1215211046/**http%3A//www.octusa.com/product/Osteoporosis.html)
G. Bone Repair:
1g. Required after break or fracture.
- Fracture Repair: Takes several months, in four steps:
1. Hematoma: After a fracture, blood escapes from ruptured blood vessels and forms a hematoma, a mass of clotted blood, between the broken bones within 6-8 hours.
2. Fibrocartilaginous Callus: Tissue repair begins, and a fibrocartilaginous callus fills the space between ends of broken bone for approx. 3 weeks.
3. Bony Callus: Osteoblasts produce trabeculae of spongy bone and changes the fibrocartilage callus to a boney callus that joins the broken bones together. Approx. 3-4 months.
- Remodeling: Osteoblasts build new compact bone at the periphery, and osteoclasts absorb the spongy bone, creating a new medullary cavity.
2g. Types of Fractures:
- Complete Fracture: Bone is broken clear through.
- Incomplete Fracture: bone is not separated into two parts.
- Simple: Does not pierce the skin.
- Compound: Does pierce the skin.
- Impacted: Broken ends are wedged into each other.
- Spiral: Break is ragged due to twisting of bone. (Mader 214)
(Insert Spiral Fracture picture http://www.flickr.com/ / http://rds.yahoo.com/_ylt=A0S0200uWG1IHIYBeomjzbkF/SIG=127bmguvs/EXP=1215211950/**http%3A//www.flickr.com/photos/spurkatory/1085629545/
III. Bones of the Axial Skeleton
A. All 206 bones of the skeleton are either in the axial skeleton or the appendicular skeleton.
B. Axial Skeleton:
1b. Lies in midline of the body and consists of skull, hyoid bone, vertebral column, and rib cage.
(Insert Axial Skeleton picture academic.wsc.edu / http://academic.wsc.edu/faculty/jatodd1/351/ch4outline.html)
C. Skull: Formed by the cranium and facial bones.
D. Cranium: Protects the brain.
- 8 bones that fit tightly together (in adults).
- In newborns, bones are not completely formed and are joined by fontanels.
1d. Some bones contain sinuses: air spaces lined by mucous membrane.
- They reduce the weight of the skull and give a resonant sound to the voice.
- Mastoid sinuses drain into middle ear. (Mastoiditis in inflammation of these sinuses.)
2d. Major bones of cranium have same names as lobes of the brain:
- Frontal (forms forehead), parietal (extend to the sides), occipital (forms base of skull, and has opening called foreamen magnum that allows the spinal cord to pass and become the brain stem), and temporal (opening that leads to middle ear).
- Sphenoid bone is shaped like a bat and extends across the floor of the cranium from one side to the other. Keystone of cranial bones because all others articulate with it. Completes side of skull and is part of forming the orbits.
- Ethmoid bone In front of sphenoid. Helps for orbits and nasal septum.
(Insert Bones of Skull picture / svhrad.com / http://rds.yahoo.com/_ylt=A0S0202QgG1IITIASQWjzbkF/SIG=11v1r1obr/EXP=1215222288/**http%3A//svhrad.com/DigLib/digitallibrary.htm)
E. The Facial Bones:
- Mandible: Lower jaw. Only movable portion of skull. Also forms chin and contains teeth sockets.
- Maxillae: Bones that form the upper jaw and the anterior portion of hard palate. Also contains tooth sockets.
- Zygomatic Bones: Cheekbone.
- Nasal Bones: Form bridge of nose.
F. Hyoid Bone:
- Not part of skull, but it is part of the axial skeleton.
- Only bone in body that does not articulate with another bone.
- Attached to temporal bones by muscles and ligaments and to the larynx by a membrane.
- Anchors the tongue. (Mader 216-217)
G. Vertebral Column:
1g. Consists of 33 vertebrae.
- Normal vertebral column has four curvatures to provide resilience and strength in posture.
- Spinal cord passes through the vertebral canal.
- Spinal nerves control skeletal muscle contractions.
- Spinous processess of vertebrae and the transverse processess are attachment sites for the muscles that move the vertebral column.
(Insert Vertebral Column picture / people.emich.edu / http://rds.yahoo.com/_ylt=A0S0202Hhm1IITIAE3WjzbkF/SIG=12ro09un5/EXP=1215223815/**http%3A//people.emich.edu/pbogle/PHED_200/outlines/chapter_07/outline.htm)

H. Types of Vertebrae:

1h. Named according to location in vertebral column.

- Cerebral- in neck.

- Atlas- holds up head.

-Axis- Allows rotation in head.

- Thoracic- ribs., etc.

I. Intervertebral Disks:

- Between vertebrae. Composed of fibrocartilage that act as padding so vertebrae don't grind together.

- Absorbs shock caused by movement.

- Degenerate with age.

J. Rib Cage (Thoracic Cage):

1j. Composed of thoracic vertebrae, ribs, cartilage and sternum.

- Protects heart and lungs.

- Moves with respiration.

(Insert Rib Cage picture / http://www.flickr.com/ / http://rds.yahoo.com/_ylt=A0S0200Com1IME8AY5OjzbkF/SIG=12juoekqm/EXP=1215230850/**http%3A//www.flickr.com/photos/jamesparkerphotography/2243044147/ )

K. Ribs:

1k. Flattened bone beginning in thoracic vertebrae and goes toward anterior thoracic wall.

- 12 pairs.

- Articulates with body and transverse process of it's thoracic vertebra.

- Upper 7 (true) ribs connect to sternum by costal cartilage.

- "False ribs", the next three pairs, connect to sternum by a common cartilage.

- "Floating ribs", the last two pairs, do not connect to sternum at all.

L. Sternum: Lies in midline of body.

-Helps protect heart and lungs.

-Flat, knife-shaped.

1l. Composed of three bones: manubrium (handle / joins with body of sternum at angle), body (blade), and the xiphoid process (point of blade / attachment site for diaphragm). (Mader 218-219)

IV. Bones of the Appendicular Skeleton

A. The bones in the pectoral and pelvic areas and their attached limbs.

1a. Pectoral Girdle and Upper Limb:

-Specialized for flexibility.

- Left and right pectoral girdles: each has a scapula (shoulder blade / visible bone in back.) and a clavicle (collarbone that extends across top of thorax. Articulates with sternum.)

2a. Glenoid cavity of scapula articulates with head of humerus.

- Allows arm to move easily in different directions, thus most prone to dislocation.

3a. Rotator Cuff: Formed by tendons that extend to humerus from four small muscles beginning in scapula.

4a. Humerus: Single long bone in arm. Fits into glenoid cavity of scapula.

5a. Capitulum and Trochlea: protuberances at far end of humerus that articulate with the radius and the unla at the elbow.

6a. Wrist has 8 carpal bones, that look like pebbles. Five metacarpal bones fan out to make palm.

- Phalanges: Bones of fingers and thumb.

B. Pelvic Girdle and Lower Limb:

1b. Pelvic Girdle is two heavy, large bones- hip bones.

2b. Pelvis: Basin made of pelvic girdle, sacrum, and coccyx.

- Bears weight of body, protects organs, and is the place of leg attachment.

3b. Coxal Bone: 3 parts:

- Ilium: largest part of coxal bones. Hips come from its flareout.

- Ischium: What we sit on. Hips occurs where it flares out.

- Pubis: Anterior part of coxal bone.

4b. Pubic Symphysis: Where the two pubic bones connect in fibrocartilaginous joint.

5b. Femur: Longest and strongest bone in body.

- Articulates with tibia.

- Patella: kneecap.

6b. Fibula: Slender bone in leg.

- Articulates with tibia and a distal lateral malleolus.

7b. Ankle has many tarsal bones.

- Instep has five elongated metatarsal bones.

- Phalanges: Bones of toes. (Mader 220-221)

(Insert Full Skeleton picture / http://www.medtrng.com/ / http://www.medtrng.com/anatomy%20lesson/bph5.htm)

V. Articulations

A. Bones joined at joints, which are either fibrous, cartilaginous, or synovial.

1a. Joints are classified according to their degree of movement. (ARIS Mader Text Website Chapter 11 Review)

- Fibrous joints, such as the sutures between bones in cranium, are not able to move.

- Cartilaginous joints are connected by hyaline cartilage, like those that joind the ribs to sternum. Slightly movable.

- Synovial joints are freely movable.

- Synovial fluid acts as lubricant.

- Ball and socket joints at hips and shoulders allow movement in all ways, even rotational.

- Elbows and knees: synovial but hinged: movement in one direction only.

B. Movements Permitted by Synovial Joints:

- Skeletal muscles are attached to bones by tendons that span joints.

- When a muscle contracts, one bone moves in relation to another bone. (Mader 222)

Leech Neuron Lab

Screen shot of Ultra-Violet Image of Neuron

Screen shot of Manipulator with Oscillope Trace

QUESTIONS ABOUT LEECH NEUROPHYSIOLOGY LAB:
(Answer these questions to get full exemplary lab credit (A-level, 18-20 points)

1. What is the electrode measuring? Electrodes measure the activity of the neurons, or the voltage of the cell. (Measurement of potential difference.) I found it very interesting that a neuron spike was only detected in the P cell that I found when a probe was used. This showed Action Potential.

2. Why use leeches in neurophysiology experiments? "The nervous system of the leech consists of the brain, the ventral nerve cord, and ganglia that are located in each segment along the nerve cord. The medicinal leech has 21 segmental ganglia, each containing 175 pairs of neurons. The relatively small number and the large size of the neurons have made leeches favorite subjects of neurobiologists." (From Leech Background Information on lab website.) So, a leech makes for a convenient subject because the neurons are large and can be located pretty easily.

3. What is the difference between a sensory and a motor neuron?
A sensory neuron transmits nerve impulses to the central nervous system after a sensory receptor has been stimulated. A motor nueron is a nerve cell that conducts nerve impulses away from the central nervous system and innervateds muscles and glands, called effectors.
4. Do you think a leech experiences pain? What is pain?

5. What were the two most interesting things about doing this lab?
1. The fact that a P cell reacts to a probe (medium) but not a forcep (high).
2. The dye injection allowing us to see the morphology of the neuron. Very cool!

6. Anything you found confusing or didn't like about the lab?
Not at all. I really enjoyed this one!

Compendium Review Chapter 14

Equilibrium

Anatomy of Ear

Astigmatic Eye

Structure and Function of Retina

Damaged Rod Cells of Eye

Anatomy of Eye

Smell

Taste

Pain Receptor in Skin

I. Sensory Receptors and Sensations
II. Proprioceptors and Cutaneous Receptors
III. Senses of Taste and Smell
IV. Sense of Vision
V. Sense of Hearing
VI. Sense of Equilibrium

I. Sensory Receptors and Sensations
A. Sensory Receptors: Special dendrites that detect certain types of stimuli.
- Extroceptors: Sensory receptors that detect stimuli from outside the body (result in taste, smell, vision, hearing and equilibrium.)
- Interoreceptors: Receive stimuli from inside the body. (Ex. Pressoreceptors respond to changes in blood pressure.) Directly involved in homeostasis; regulated by a negative feedback mechanism.
B. Types of Sensory Receptors: 4 Categories
1b. Chemoreceptors: Respond to chemical substances in immediate area. (taste and smell, and various other organs sensitive to internal stimuli.)
2b. Pain Receptors: Type of chemoreceptor. Naked dendrites that respond to chemicals released by damaged tissue. Protective- alert us of danger.
(Insert Pain Receptor in Skin picture / fig.cox.miami.edu / http://fig.cox.miami.edu/~cmallery/150/neuro/senses.htm)
3b. Photoreceptors: Respond to light energy. (Eyes) Stimulation results in color vision.
4b. Mechanoreceptors: Stimulated by mechanical forces, which often result in pressure of some sort. (hearing, balance)
5b. Thermoreceptors: Located in hypothalamus and skin. Stimulated by changes in temperature. (warm receptors- temps rise. cold receptors- temps fall.) (Mader 274)
C. How Sensation Occurs:
- Sensory receptors respond to stimulus from body or environment.
- These receptor cells trigger action potential in connecting sensory neurons.
- Spinal cord and/or brain interpret and analyze information.
(Frolich PowerPoint Slide 24), and initiate motor response. (Mader 275)
1c. Sensation: The conscious perception of stimuli.
2c. Review: Sensory receptors are first element in reflex arc. Reflex actions become known to us only when sensory info reaches the brain. The brain then integrates this info with other info from other sensory receptors.
3c. All sensory receptors initiate nerve impulses, and the resulting sensation depends on which part of the brain receives the impulse.
4c. Integration: The summing up of signals. Occurs BEFORE sensory receptors initiate the nerve impulse.
5c. Sensory Adaptation: A type of integration. A decrease in response to stimulus. (When you get "used" to a smell, etc.) (Mader 275)
II. Proprioceptors and Cutaneous Receptors
A. Sensory Receptors: 3 types
- Proprioceptors: Mechanoreceptors involved in reflex actions that maintain muscle tone, equilibrium, and posture. They detect the degree of muscle relaxation, stretch of tendons, and movement of ligaments. (Mader 276) More simply put, "Proprioception—gives body position by sensing muscle tension." (Frolich PowerPoint Slide 27)
B. Cutaneous Receptors: Skin is composed of two layers, the epidermis and dermis.
1b. Dermis contains cutaneous receptors: Causes skin to be sensitive to the touch, pressure, pain, and termperature.
2b. There are three types of cutaneous receptors that are sensitive to fine touch: Meissner corpuscles, Merkel disks, and root hear plexus.
3b. Two types of cutaneous receptors sensitive to pressure: Pacinian corpuscles and Ruffini endings.
4b. Temperature Receptors: Free nerve endings in the epidermis.
C. Pain Receptors: Internal organs have pain receptors, as do the skin. Sensitive to chemicals released by damaged tissues.
1c. Referred Pain: Occurs when pain receptors are stimulated from the skin as well as the internal organs. (Mader 277)
III. Senses of Taste and Smell
A. Taste and Smell are chemical receptors because the receptors are sensitive to molecules in the food we eat and air we breathe.
1a. Bear chemoreceptors: Plasma membrane receptors that bind to particular molecules. Two Types:
- Some respond to distant stimuli (olfactory cells), and
- some respond to direct stimuli (taste cells).
B. Taste: Approx. 3,000 taste buds on tongue. 4 primary types:
- Sweet
- Sour
- Salty
- Bitter
1b. The brain receives taste information when molecules bind to receptor proteins of the microvilli, and nerve impulses are generated in sensory nerve fibers that go to the brain. (Mader 278)
(Insert Taste picture / Frolich PowerPoint Slide 29)
C. Sense of Smell: Approx. 80-90% of what we think is taste is actually from the sense of smell.
1c. 10-20 million olfactory cells (which are modified neurons)
are located wihtin the olfactory epithelium in the roof of nasal cavity.
2c. Each olfactory cell ends in a bunch of approx. five olfactory cilia, which haave the receptor proteins for odor molecules.
3c. The brain receives smell information when nerve fibers from like olfactory cells lead to the same neuron in the olfactory bulb, and extension of the brain. An odor has many odor molecules, which activiate a characteristic combination of receptor proteins. Neurons then communicate this ifo via the olfactory tract to the corresponding areas of the cerebral cortex.
4c. Smell actually deteriorates with age! (Mader 278-279)
(Insert Smell picture / Frolich PowerPoint Slide 30)
IV. Sense of Vision
A. Requires work of eyes and brain. Eyes process a good deal of stimuli before nerve impulses are sent to the brain. Still, Approx. 1/3 of cerebral cortex takes part in processing visual info.
B. Anatomy and Physiology of the Eye
1b. Eyeball is an elongated sphere.
- Three layers:
- Layer 1: Sclera: (outer layer)that includes cornea ("window" of the eye).
- Layer 2: Choroid: (middle, thin, dark layer. Absorbs light rays that photoreceptors have not absorbed.) Choroid becomes the iris, which regulates the size of the pupil, the hole in the center of the iris that allows light to enter the eyeball.)
- Ciliary Body: Contains ciliary muscle, to control shape of lens for near and far vision.
- Lens: Attached to ciliary body by ligaments, it divides eye into two compartments.
1. Compartment in front of lens is the anterior compartment. Filled with clear, watery fluid called aqueous humor.
2. Compartment behind lens in the posterior compartment.
- Layer 3: Retina: Located in posterior compartment, filled with clear, gel material called vitreous humor. Also contains rod cells (very sensitive to light, but does not see color) and cone cells (require bright light, sensitive to different wavelengths of light, and can distinguish colors).
- Fovea Centralis: Region of retina where cone cells are dense. Vision is most acute here.
- Sensory fibers from retina form optic nerve, which takes nerve impulses to visual cortex of brain.
C. Function of Lens: Cornea focuses images on retina. Focusing continues as rays go through lens and humors. Image is smaller than object, and is inverted and reversed.
D. Visual Accomodation: Occurs for close vision. Lens rounds up, to bring image to focus on retina.
E. Visual Pathway to Brain: Once light has been focused on photoreceptors in retina, integration occurs in retina, and then nerve impulses begin before the optic nerve transmits them to the brain.
(Insert Anatomy of Eye picture / www.rennard.org / http://www.rennard.org/alife/english/biomintrgb.html)
F. Function of Photoreceptors: These rod and cone cells both have outer segment joined to inner segment by a stalk. Pigment molecules are embedded in membrane of disks in outer segment.
- Rods are sensitive to light- suited for night vision.
- Cones are activated by bright light, and allow us to detect fine detail and color of an object.
(Insert Damaged Rod Cells of Eye picture / www.medicalprogress.org)
G. Function of Retina: Retina has three layers of neurons.
1. Layer closest to choroid has rod cells and cone cells.
2. Middle layer has bipolar cells.
3. Innermost layer has ganglion cells, whose sensory fibers turn into the optic nerve.
1g. Since only rod and cone cells are sensitive tolight, light must penetrate to the back of the retina before they are stimulated. (Mader 282)
2g. Integration occurs when signals pass to bipolar and ganglion cells. They then create the nerve impulses that are taken to the optic nerve to the visual cortex of brain.
H. Blind Spot: Area of no vision. No rods and cones are present where the optic nerve exits the retina.
I. From Retina to Visual Cortex
1i. Optic Chiasma: Optic nerves carry nerve impulses from eyes to optic chiasma, which is x shapted, and formed by the crossing of optic nerve fibers.
2i. Images are "righted" in brain.
(Insert Retina Receptors picture / Frolich PowerPoint Slide 32)
J. Abnormalities of Eye
1j. Color blindness.
2j. Misshapen eyeballs.
3j. Nearsightedness: Can see close objects better than those at a distance. Elongated eyeballs.
4j. Farsighted: Cannot see close objects. Shortened eyeballs.
5j. Astigmatism: Cornea or lens is uneven, and images are funny.
(Mader 284)
(Insert Astigmatic Eye picture / www.daviddarling.info / http://www.daviddarling.info/encyclopedia/A/astigmatism.html)
V. Sense of Hearing
A. Ear has two sensory functions: hearing and balance (equilibrium).
1a. Sensory receptors for both functions are located in inner ear, consisting of hair cells with long microvilli that are sensitive to mechanical stimulation. Mechanoreceptors.
B. Anatomy and Physiology of Ear: Ear has three divisions:
1. Outer Ear: Consists of pinna (external flap) and auditory canal. Secretes ear way, to hellp protect against entrance of foreign materials.
2. Middle Ear: Begins at tympanic membrane (eardrum) and ends at bony wall that has two small openings covered by membranes, called oval window and round window. Ossicles (three small bones) are found between tympanic membrane and oval window.
- Auditory Tube: (eustachian tube) Extends from middle ear to nasopharynx, permitting equalization of air pressure.
3. Inner Ear: Filled with fluid. Has three areas:
- 1. Semicircular canals
- 2. Vestibule (Both of these are concerned with equilibrium.)
- 3. Cochlea: concerned with hearing.
C. Auditory Pathway to Brain: Sound pathway begins with auditory canal, but then hearing requires other parts of the ear, the cochlear nerve and brain.
1c. Through auditory canal and middle ear: Hearing begins when sound waves enter the auditory canal. Sound waves travel by successive vibrations of molecules. Stapes strikes the membrane of oval window, it vibrates, and the pressure is passed to fluid within the cochlea.
2c. From cochlea to auditory cortex: Spiral organ: located in the cochlear canal. Consists of little hair cells and gel material called tectorial membrane.
- Pressure waves move from vestibular canal to tympanic canal.
- Nerve imulses begin in cochlear nerve and travel to brain. (Mader 286-287)
(Insert Anatomy of Ear picture / www2.hawaii.edu / http://www2.hawaii.edu/~heirakuj/ear.htm)
V. Sense of Equilibrium
A. Vestibular nerve takes impulses to brain stem and cerebellum. Through this communication, it helps us achieve equilibrium. Proprioceptors are also necessary.
B. Rotational Equilibrium Pathway:
- Mechanoreceptors in the semicircular canals detect rotational and / or angular movement of the head (rotational equilibrium.)
1b. Ampulla: Base of each of three canals, slightly enlarged.
- Each ampulla responds to head rotation in a different plane of space.
- Brain uses info from hair cells wihin ampulla of semicircular canals to maintain equilibrium through motor output to various skeletal muscles that can right the position of the body.
C. Gravitational Equilibrium Pathway: Mechanoreceptors in utricle and saccule detect movement of head in vertical or horizontal planes (gravitational equilibrium).
- Utricle and saccule are two membranous sacs located in inner ear. (Mader 291)
(Insert Equilibrium picture / Frolich PowerPoint Slide 34)